1. Field of the Invention
This invention relates to a printed circuit board testing apparatus for testing an open circuit and current leakage or conductivity of a circuit pattern formed on a printed circuit board, and a probe device for use in such an apparatus.
2. Discussion of the Related Art
There has been a circuit board testing apparatus which tests an open circuit and current leakage or conductivity of a circuit pattern formed on a printed circuit board by rendering a single contact needle or a number of contact needles of a probe device to come into contact with a specified position of the circuit pattern formed on the circuit board as shown in Japanese Unexamined Patent Publication No.6-186271. However, there has been a problem that when the contact needle comes into contact with the circuit pattern, the circuit pattern receives a considerable impact and a noticeable stress occurs in the contact needle, resulting in an incorrect measurement. To solve this problem, accordingly, some technologies have been proposed.
Japanese Unexamined Patent Publication No. 9-178771 discloses a probe device in which a contact needle is moved or shifted to a position near the circuit pattern at a high speed, and the contact needle is then moved to the circuit pattern at a slow speed so as to assure a soft contact. Also, Japanese Unexamined Patent Publication No. 9-113536 discloses a probe device provided with a coil spring on an upper portion of a contact needle to absorb an impact at contact.
However, these probe devices have the following drawbacks. The probe device featuring the speed change requires an increased measurement time or testing time to assure a soft contact. The probe device featuring the coil spring cannot suppress the stress on the contact needle sufficiently. Further, the contact needle of these probe devices suffers considerable abrasion, and has some likelihood of breaking.
It is an object of the present invention to provide a circuit board testing apparatus and a probe device which are free from the problems residing in the prior art.
According to an aspect of the invention, a probe device comprises a holder mountable to a circuit board testing apparatus, and a contact needle attachable to the holder. The contact needle is operable to resiliently bend in a specified direction immediately after coming into contact with a circuit board.
According to another aspect of the invention, a circuit board testing apparatus comprises a table for supporting a circuit board to be tested, and a tester unit carrying a plurality of probe devices. Each probe device is provided with a holder mountable to a main body of the test unit, and a contact needle attachable to the holder, and operable to resiliently bend in a specified direction immediately after coming into contact with the circuit board.